Radiographic and Clinical Evaluations of Mandibular Implant-Supported Overdentures Supported by Conventional and Zirconia CAD/CAM Bars: A Randomized Clinical Trial

Evaluation Of Mandibular Implant-Supported Overdenture: A Comparative Study of Conventional Bar Versus Zirconia CAD/CAM Bars

This randomized clinical trial aimed to evaluate the radiographic and clinical evaluations of mandibular implant-supported overdentures supported d by two different bar materials。 Completely edentulous patients received two implants in the mandibular canine region and were rehabilitated with overdentures supported by a conventional cobalt-chromium bar and a zirconia CAD/CAM bar。 Radiographic marginal bone loss around implants, crestal bone height changes posteriorly and clinical peri-implant parameters were assessed at baseline,6 months, and 12 months to compare the performance of both bar materials。

Study Overview

• Status: Completed
• Conditions: Edentulous Mandible
• Intervention / Treatment: Device: Cobalt-Chromium Bar Attachment; Device: Zirconia CAD/CAM Bar Attachment

Detailed Description

This randomized clinical trial was conducted to compare the radiographic and clinical outcomes of mandibular implant-supported overdentures supported by conventional cobalt-chromium bars and zirconia CAD/CAM bars。 Eligible completely edentulous patients were selected according to predefined inclusion and exclusion criteria。

All participants received two endosseous dental implants placed in the mandibular canine regions following a standardized surgical protocol。 After a healing period, patients were randomly allocated into two groups。 In the first group, overdentures were supported by using a conventional cast cobalt-chromium bar, while in the second group, overdentures were supported by using a zirconia CAD/CAM-fabricated bar。

Radiographic evaluations of marginal bone loss around implants and crestal bone height changes posteriorly were performed using cone beam computed tomography and clinical peri-implant parameters, including pocket depth, plaque index, bleeding index, and mobility were evaluated at baseline,6 months and after 12 months。

The primary outcome of this study was the evaluation of radiographic marginal bone loss around implants and crestal bone height changes posteriorly, while secondary outcomes included peri-implant soft tissue health parameters。 The collected data were statistically analysed to compare bone stability and clinical performance associated with the two bar materials over the observation period。

• Study Type: Interventional
• Enrollment (Actual): 12
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Egypt
  • Nasr City
    • Cairo, Nasr City, Egypt
      • Faculty of Dental Medicine for Girls, Al-Azhar University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• • Patients age range was between 50-60 years old.

  • Only male patients were selected to participate in this study.
  • All patients were apparently free from any systemic or debilitating diseases that might affect bone metabolism or delay post-operative healing.
  • Patients were free from any temporo-mandibular joint disorders.
  • Patients were free from any neuromuscular or bony disorders, and medically free from any neurologic disorder affecting the neuro-muscular system.
  • Patients' residual alveolar ridges were covered with firm, healthy mucosa, free from any signs of inflammation, ulceration, or flabby tissue.
  • Mandibular edentulous alveolar ridge areas had sufficient width and height of alveolar bone.
  • Patients exhibited Angle Class I maxillo-mandibular relationship and sufficient inter-arch space.
  • Patients had good oral hygiene.
  • A period of at least six months up to one year had elapsed from the last extraction.

Exclusion Criteria:

• • Patients with systemic diseases that might affect bone quality, contribute to bone resorption, increase surgical risk, or delay/complicate post-operative healing.

  • Patients with parafunctional habits such as bruxism, clenching, or grinding.
  • Patients with residual ridge covered by inflamed, ulcerated, or flabby mucosa.
  • Patients with inadequate inter-arch space.
  • Patients with abnormal tongue behavior and/or size.
  • Patients with xerostomia or excessive salivation.
  • Heavy smoker patients and alcoholic patients.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Conventional Cobalt-Chromium Bar; participants received mandibular implant-supported overdentures supported by a conventional cast cobalt-chromium bar	Device: Cobalt-Chromium Bar Attachment; A conventional cast cobalt-chromium bar used to retain a mandibular implant-supported overdenture
Experimental: Zirconia CAD/CAM Bar; participants received mandibular implant-supported overdentures supported by a Zirconia CAD/CAM-fabricated bar	Device: Zirconia CAD/CAM Bar Attachment; A zirconia CAD/CAM-fabricated bar used to retain a mandibular implant-supported overdenture

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Marginal bone loss around Implants	Radiographic assessment of marginal bone loss around mandibular implants and crestal bone height changes posteriorly using cone-beam computed tomography (CBCT)	Baseline,6 months, and 12 months
Posterior crestal bone height changes of the mandibular ridge	Radiographic assessment of posterior crestal bone height changes of the mandibular ridge using cone-beam computed tomography (CBCT)	Baseline,6months,12months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peri-Implant probing depth	Peri-implant probing depth measured using a calibrated periodontal probe	Baseline,6 months, and 12 months
plaque index around implants	Plaque accumulation around implants assessed using Silness and Löe plaque index	Baseline, 6 months, and 12 months
Bleeding on probing around implants	Bleeding on probing around implants assessed using a calibrated periodontal probe	Baseline, 6 months, and 12 months
Implant mobility	Implant mobility evaluated using clinical manual assessment (two rigid instrument technique)	Baseline, 6 months, and 12 months

Collaborators and Investigators

• Sponsor: Sara Mohamed Fakhry Meligy Mohamed
• Collaborators: Al-Azhar University

Study record dates

Study Major Dates

• Study Start (Actual): July 18, 2022
• Primary Completion (Actual): June 17, 2025
• Study Completion (Actual): June 19, 2025

Study Registration Dates

• First Submitted: February 3, 2026
• First Submitted That Met QC Criteria: February 17, 2026
• First Posted (Actual): February 24, 2026

Study Record Updates

• Last Update Posted (Actual): February 24, 2026
• Last Update Submitted That Met QC Criteria: February 17, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Crestal bone loss; Mandibular Implant-Supported Overdenture; Cobalt-Chromium bar; Zirconia CAD/CAM bar; Mandibular implants
• Other Study ID Numbers: P-PR-22-02

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No